.book-hd .back {
  position: fixed;
  top: 7px;
  left: 13px;
  z-index: 2;
  display: block;
  width: 20px;
  height: 20px;
  font-size: 22px;
  color: #424242;
}

.book-detail {
  padding: 15px;
  margin-top: 44px;
}

.book-btn-group .auto-play-btn {
  display: block;
}

.book-btn-group .stop {
  display: none;
}
